Rotary vane expander

ABSTRACT

The present disclosure relates to a rotary vane expander for generating mechanical energy from the expansion of a gaseous medium comprising a housing, an inlet and an outlet for the gaseous medium and to a rotor arranged in the housing. Provision is made in this respect in accordance with a first aspect that the inner contour of the housing has two or more stroke regions which are in communication with the inlet for the gaseous medium so that the gaseous medium expands simultaneously in the two or more stroke regions during the operation of the energy recovery system.

TECHNICAL FIELD

The present disclosure relates to a rotary vane expander for generating mechanical energy from the expansion of a gaseous medium comprising a housing, an inlet and an outlet for the gaseous medium and to a rotor arranged in the housing.

BACKGROUND AND SUMMARY

Such rotary vane expanders can be used, for example, in energy recovery systems to generate mechanical energy from the waste heat of a plant by the drive of the rotary vane expander. It can be used, for example, for generating electricity.

It is the object of the present disclosure in this respect to provide a rotary vane expander which is optimized for use with a gaseous medium.

This object is achieved in accordance with the present disclosure through various examples as described herein.

In accordance with a first aspect, the present disclosure in this respect includes a rotary vane expander for generating mechanical energy from the expansion of a gaseous medium comprising a housing, an inlet and an outlet for the gaseous medium and a rotor arranged in the housing. Provision is made in accordance with the present disclosure in this respect that the inner contour of the housing has two or more ranges which are in communication with the inlet for the gaseous medium so that the gaseous medium expands simultaneously in the two or more stroke regions during the operation of the energy recovery system. In a particular embodiment, the inner contour in this respect has exactly two stroke regions.

The rotary vane expander having two or more strokes has the advantage in this respect that the thermal and mechanical loads acting on the rotor in operation no longer act unilaterally on only one side. The service life and smooth running of the rotor are hereby substantially improved.

The individual stroke regions in this respect advantageously extend in each case over ranges of angles of rotation of the rotor of equal magnitudes. With two stroke regions, each stroke region in this respect extends over 180° in each case; with three stroke regions over 120°, etc.

Further advantageously, the inner contour of the housing can be identical for all stroke regions. A particularly uniform loading of the rotor is hereby achieved.

Alternatively or additionally, the control slits of the housing can also be identical for all stroke regions. This provides that all stroke regions of the rotary vane expander are controlled synchronously.

In a particular embodiment of the rotary vane expander in accordance with the present disclosure, the inner contour of the housing is designed asymmetrically with respect to the rotary region respectively associated with a stroke. The individual stroke regions are thus respectively not arcuate per se. This in particular has the advantage that the expansion phase of the rotary vane expander can be increased.

The rotary region associated with the expansion phase in this respect in particular makes up more than 50% of the total rotary region of the rotor associated with the expansion phase. The rotary region associated with the expansion phase in this respect optionally makes up more than 60%, further advantageously more than 75% of the total rotary region of the rotor associated with it.

In a second aspect, the present disclosure includes a rotary vane expander for generating mechanical energy from the expansion of a gaseous medium comprising a housing, an inlet and an outlet for the gaseous medium and a rotor arranged in the housing. Provision is made in this respect in accordance with the present disclosure that the vanes are guided by a compulsory guide ring on their side remote from the housing. The compulsory guide ring in this respect provides that the vanes are always in contact with the inner contour of the housing. The compulsory guide ring is for this purpose advantageously fixedly connected to the housing and thus forces the vanes of the rotor rotating with the rotor into a position in which their outer edges are in contact with the inner contour of the housing. A sprung support of the vanes can in particular be omitted in this respect.

In a particular embodiment, it is taken into account in this respect that the contact regions of the vanes with the inner contour of the housing have a radius of curvature greater than zero so that the contact line of the vanes is displaced with the inner contour on the rotary movement of the rotor on the radius of curvature of the contact regions. Provision is advantageously made in this respect that the compulsory guide ring has a contour which takes this displacement into account.

The radial spacing between the outer contour of the compulsory guide ring and the inner contour of the housing is thus, unlike in the prior art, not identical for all radii since in this case the displaced contact line of the contact region of the vanes with the inner contour of the housing would result in different gap widths depending on the position of the rotor. The compulsory guide ring is rather advantageously formed so that the radial distance between the inner contour of the housing and the compulsory guide ring varies with the angle of rotation so that an ideal contact of the contact region of the vane and the inner contour of the housing is present in every rotary position.

In a third aspect, the present disclosure includes a rotary vane expander for generating mechanical energy from the expansion of a gaseous medium comprising a housing, an inlet and an outlet for the gaseous medium and a rotor arranged in the housing. Provision is made in accordance with the present disclosure in this respect that sealing segments of a sealing ring are arranged between the vanes at the end faces of the rotor for the lateral sealing with the housing. The sealing segments in this respect allow a particularly good sealing of the end faces of the rotor with the end faces of the housing.

The end faces advantageously have cut-outs for this purpose in which the sealing segments are arranged. Further advantageously, the end faces of the rotor have a ring groove for this purpose in which the individual segments are arranged so that they form a sealing ring overall.

Further advantageously, the individual vanes extend, however, from one end face of the housing up to the opposite end face and thus separate the individual segments from one another.

Pressure elements are further advantageously provided which press the sealing segments toward the housing. An even better sealing is hereby made possible. Furthermore, different orders of the coefficients of expansion of the housing and the rotor can hereby be taken into account.

In a first advantageous embodiment, the pressure elements in this respect include a spring which presses the sealing segments toward the housing.

In a second embodiment, the pressure elements can include a pressure passage which applies pressure from the pressure chamber associated with the segment onto the rear side of the segments and hereby presses against the housing. This has the advantage that the contact pressure of the sealing segments is dependent on the pressure in the respective pressure chamber and thus increases as the pressure in the pressure chamber increases.

In accordance with a fourth aspect, the present disclosure in this respect includes a rotary vane expander for generating mechanical energy from the expansion of a gaseous medium comprising a housing, an inlet and an outlet for the gaseous medium and a rotor arranged in the housing. Provision is made in accordance with the present disclosure in this respect that the rotor comprises two or more rotor sections which are seated next to one another on a common axis and are each separated from one another by a pressure plate. Provision can alternatively or additionally be made that the housing comprises two or more housing sections which are arranged next to one another in the axial direction of the rotor (e.g., in a direction of an axis of rotation of the rotor) and surround the rotor. The capacity of the rotary vane expander can be set without a problem to a desired value by the use of a corresponding number of sections due to such a design of the rotor or of the housing from a plurality of sections.

In this respect, the rotor sections and/or housing sections are advantageously made identical. Provision can alternatively or additionally be made that each housing section has the same inner contour. The use of a plurality of similar rotor sections or housing sections thus allows a particularly cost-saving construction of the rotary vane expander.

The axis of the rotor is in this respect advantageously supported both at the outer end faces of the housing and at the pressure plates. Provision can furthermore be made that the individual housing sections are connected to the interposed pressure plates.

The present disclosure in this respect in particular includes a rotary vane expander in which at least three rotor sections are provided, with the housing having control slits in the peripheral region for controlling at least one of the inwardly disposed rotor sections. The outwardly disposed rotor sections can in contrast also be controlled via control slits in the region of the end faces of the housing. Alternatively, however, these rotor sections can also be controlled via control slits in the peripheral region to minimize the production effort for different housings.

Further advantageously, the housings are in this respect designed so that the individual rotor sections and rotary vane expander sections formed hereby are controlled identically.

In accordance with a fifth aspect of the present disclosure, it includes a rotary vane expander for generating mechanical energy from the expansion of a gaseous medium comprising a housing, an inlet and an outlet for the gaseous medium and a rotor arranged in the housing. Provision is made in accordance with the present disclosure in this respect that the rotor of the rotary vane expander is supported via ball bearings with ceramic balls. This in particular allows a lubrication-free support of the rotor since the ceramic balls are sufficiently lubricated by the gaseous medium to ensure a reliable operation even without oil lubrication. The support rails of the ball bearings are advantageously made of steel in this respect.

In particularly advantageous embodiments of the present disclosure, two or more of the above-described five aspects of the present disclosure are combined with one another.

The better radial sealing in accordance with the second aspect can in particular be combined with the better lateral sealing in accordance with the third aspect in order thus to achieve the seal tightness required for the use with a gaseous medium.

The shape of the housing in accordance with the first aspect can furthermore be combined with the better sealing possibilities in accordance with the second and/or third aspects of the present disclosure. Unfavorable changing pressure conditions which may be induced by the shape in accordance with the present disclosure can thus be compensated.

The modular structure in accordance with the fourth aspect can furthermore be combined with the shape of the housing in accordance with the present disclosure in accordance with the first aspect and/or with the improved seal tightness in accordance with the second and/or third aspect in order thus to realize different stroke volumes with acceptable costs.

The support of the rotor in accordance with the fifth aspect can further be used in rotary vane rotors in accordance with all the other aspects to realize a lubrication-free support.

Three, four or all five aspects of the present disclosure can naturally also be combined with one another in this respect.

The general design and the function of a rotary vane expander in accordance with one of the above-described aspects of the present disclosure will be briefly presented again.

The rotary vane expander has a housing, an inlet and an outlet for the gaseous medium and has a rotor arranged in the housing. In this respect, slits are provided in the rotor and vane plates are displaceably arranged in them. The individual chambers or cells of the rotary vane expander are thus formed by the outer contour of the rotor, by the inner contour of the housing and by respectively adjacent vane plates. On a rotary movement of the rotor, the individual vanes in this respect follow the inner contour of the housing and are moved up and down in the guide slits of the rotor. A stroke region of an expander in this respect corresponds to the rotary region of the outer contour in which a vane is moved from a completely moved in position into a completely moved out position and back again. In operation, the gaseous medium thus flows through the inlet via control slits of the housing at pressure into the vane cells, expands there under the movement of the rotor and then flows via further control slits of the housing to the outlet.

The rotary vane expander in accordance with the present disclosure advantageously has more than four vanes, further advantageously six or more vanes. The number of vanes can in this respect amount to fewer than 20, further advantageously fewer than 15 vanes. The vanes are advantageously in this respect arranged about the rotor with respective identical rotary angle intervals.

The control slits which connect the vane cells with the inlet for the gaseous medium are in this respect advantageously arranged in the peripheral region of the rotor, i.e. in the region of the inner contour facing the rotor. The control slits which connect the vane cells to the outlet for the gaseous medium are in contrast advantageously arranged in the region of the end faces.

The housing can in this respect furthermore be made up of end-face cover sections and a jacket region arranged between them. In this respect, the control slits for connecting to the inlet are advantageously arranged in the jacket region and the control slits for connecting to the outlet are in arranged in one or both cover sections.

In addition to the above-described rotary vane expanders in accordance with the five aspects of the present disclosure, the present disclosure furthermore includes an energy recovery system having such a rotary vane expander.

Combinations of the five aspects of the present disclosure are naturally in this respect also possible with respect to the energy recovery system as was already presented above with respect to the rotary vane expanders.

The energy recovery system can in this respect have a fluid circuit in which a medium circulates which expands in the expander. The energy recovery system can be used to convert thermal energy via the rotary vane expander into mechanical shaft power.

The energy recovery system can in this respect have a pump, a heat exchanger, the rotary vane expander and a condenser. The pump is used in this respect to increase the pressure of the medium in the circuit. The medium is then heated, vaporized and overheated in the heat exchanger. The expansion phase of the now gaseous medium takes place in the rotary vane expander. In this respect, mechanical power is output at an output shaft of the expander. The fluid is then cooled and liquefied in the condenser.

In this respect, in particular a liquid having a boiling point between 50° C. and 120° C. can be used as the medium, for example water, an alcohol such as ethanol and/or R245.

The present disclosure furthermore includes a method for operating an energy recovery system in accordance with the present disclosure such as was described above. In accordance with the present disclosure, provision is made that a gaseous medium flows into the rotary vane expander and expands there while outputting mechanical energy. The energy recover system in accordance with the present disclosure in this respect advantageously works in accordance with the Clausius-Rankine principle.

The present disclosure furthermore includes a method for manufacturing an energy recovery stem in accordance with the second aspect of the present disclosure. Provision is made in this respect in accordance with the present disclosure that the outer contour of the compulsory guide ring is determined while taking account of the displacement of the contact line. It can hereby in particular be taken into account that the contact regions of the vanes with the inner contour of the housing usually have a radius of curvature greater than zero so that the contact line of the vanes with the inner contour of the housing is displaced on the rotary movement of the rotor and hereby the radial distance between the inner contour of the housing and the outer contour of the compulsory guide ring does not correspond to the actual spacing between the two contact lines of the vane with the inner contour of the housing and the outer contour of the compulsory guide ring.

In accordance with the present disclosure, this is now taken into account in the determination of the desired outer contour of the compulsory guide ring. The spacing between the two contact lines can hereby be set exactly to the desired dimension.

The present disclosure furthermore includes a method of manufacturing an energy recovery system having a rotary vane expander for generating mechanical energy from the expansion of a gaseous medium, with the rotary vane expander having an inlet and an outlet for the gaseous medium, a housing and a rotor arranged in the housing. Provision is made in this respect in accordance with the present disclosure that depending on the desired stroke volume the rotor is made up of one, two or more rotor sections which, when two or more rotor sections are used, are placed next to one another on a common axis and are each separated from one another by a pressure plate. Provision can alternatively or additionally be made that the housing is also made up of a plurality of housing sections which, when two or more housing sections are used, are arranged next to one another in the axial direction of the rotor and are connected to a pressure plate. The method in this respect in particular serves the manufacture of an energy recovery system in accordance with the fourth aspect of the present disclosure.

The individual aspects of the present disclosure will now be described in more detail with reference to embodiments and to drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a schematic diagram of an energy recovery system in which a rotary vane expander in accordance with the present disclosure can be used.

FIG. 2 shows a p-V diagram for operating such an energy recovery system in accordance with the Clausius-Rankine principle.

FIG. 3 shows an embodiment of the first aspect of the present disclosure in which the rotary vane expander has two or more stroke regions, with here one of these stroke regions being shown with an asymmetric inner contour of the housing.

FIG. 4 shows an embodiment of the second aspect of the present disclosure, in which a compulsory guide ring is used for guiding the vanes, with the rotary vane expander being shown in a side view.

FIG. 5 shows a detailed view for the more detailed explanation of the embodiment of the compulsory guide ring in accordance with the second aspect.

FIG. 6 shows a first embodiment of the third aspect of the present disclosure, in which sealing segments are used for sealing the end faces of the rotor, with the rotary vane expander being shown in a sectional view in the axial direction.

FIG. 7 shows a second embodiment of the third aspect of the present disclosure, with the sealing segment preloaded by a spring in this embodiment and the end face of the rotor being shown in an exploded view.

FIG. 8 shows an embodiment of the modular structure in accordance with the fourth aspect of the present disclosure by which the rotary vane expander in accordance with the present disclosure can be set up from one or more sections depending on the desired stroke volume. FIGS. 3-8 are drawn approximately to scale, although other relative dimensions may also be used.

DETAILED DESCRIPTION

An energy recovery system is shown in FIG. 1 in which a rotary vane expander in accordance with the present disclosure can be used. The energy recovery system in this respect has a fluid circuit 1 in which a medium circulates. The energy recovery system can be used to convert thermal energy via the expander 4 into mechanical shaft power.

In this respect, the energy recovery system has a pump 2, a heat exchanger 3, the expander 4 and a condenser 5. The pump 2 is used in this respect to increase the pressure of the medium in the circuit. The medium is then heated, vaporized and overheated in the heat exchanger 3. The expansion phase of the now gaseous medium takes place in the expander 4. In this respect, mechanical power is output at an output shaft of the expander.

The fluid is then cooled and liquefied in the condenser 5. The energy recovery system in accordance with the present disclosure can furthermore have a tank and, optionally, a filter which were not shown in FIG. 1, however, for reasons of clarity.

The operation of the energy recovery system in this respect advantageously takes place in accordance with the Clausius-Rankine principle whose p-V diagram is shown in FIG. 2. The line 6 in this respect corresponds to the pressure application on the medium in the pump 2, the line 7 to the heating, vaporizing and overheating of the medium in the heat exchanger 3, the line 8 to the expansion in the expander 4 and the line 9 to the condensation in the condenser 5.

A liquid having a boiling point between 50° C. and 120° C., for example water, ethanol or R245 is advantageously used as the medium in the circuit.

In accordance with the present disclosure, a rotary vane expander is now used as the expander in such an energy recovery system. The efficiency of such a rotary vane expander depends in this respect on the geometrical and mechanical properties of the expander. The most important geometrical parameters of the rotary vane expander, in addition to the basic parameters of the rotary vane expander such as the inner diameter of the housing and the rotor height, are the expansion ratio and the curve of the isentropic expansion.

A rotary vane expander in accordance with the present disclosure in this respect includes a housing and a rotor arranged in the housing. In this respect, the rotor carries a plurality of vanes which are displaceably supported at the rotor and whose outer edges are in contact with the inner contour of the housing. The individual vanes hereby define chambers. The inner contour of the housing in this respect has a distance from the axis of rotation of the rotor varying over the range of the angle of rotation of the rotor. The volume of the vane cells formed by the individual vanes hereby varies.

The rotary vane expander furthermore has an inlet for the gaseous medium through which the latter can flow into the rotary vane expander. The rotary vane expander furthermore has an outlet for the expanded gaseous medium. The inlet and the outlet are in this respect in communication with the stroke volume of the rotor via a slit control. In this respect, openings or slits in the end faces and/or in the peripheral region of the housing provide a connection of the vane cells to the inlet for the gaseous medium when the volume of the vane cells is low due to the angle of rotation of the rotor. On a rotation of the rotor, the volume of the vane cells expands with the gas enclosed therein. The expansion of the gas in this respect drives the rotor. If the volume of the respective vane cells was expanded by the rotor, they come into contact with further openings or slits which establish a connection to the outlet for the now expanded gaseous medium. Such a rotary vane expander thus works exactly conversely to a rotary vane pump.

The vanes of the rotary vane expander are in this respect advantageously supported in slits of the rotor and extend away from the axis of rotation of the rotor in the radial direction. In this respect, between 6 and 14 vanes can be used for the rotary vane expander, for example.

The present disclosure now optimizes such a rotary vane expander in a plurality of aspects independent of one another. The individual mutually independent aspects which will now be described in the following can, however, also be used in combination with one another.

An embodiment of a first aspect of the present disclosure is now shown in FIG. 3. FIG. 3 shows a section through the rotor 11 whose outer contour is circular. In this respect, slits 13 are provided in the rotor and vanes 12 are supported in them displaceable in the radial direction. The outer edges of the vanes 12 in this respect contact the inner contour 10 of the housing.

The rotary vane expander in accordance with the present disclosure is in this respect designed with two strokes, that is, each individual vane is completely pressed into the rotor and is completely pushed out of it twice on a rotation by 360°. In other words, each vane cell of the rotary vane expander passes through its maximum volume twice and its minimum volume twice on a rotation of the rotor by 360°.

Each of the two stroke regions is in this respect of equal size with respect to the angle of rotation of the rotor, that is, the housing in each case has two stroke regions having an extent of 180°. Only the upper stroke region is shown in FIG. 3. The lower stroke region is in contrast designed with point symmetry with respect to the longitudinal axis of the rotor 11.

The slit control and the inner contour of the housing are in this respect designed so that the expansion of the gaseous medium takes place simultaneously and synchronously in both stroke regions. In this respect, both stroke regions are optionally designed symmetrically with respect to their inner contour and with respect to the slit control.

In accordance with the present disclosure, an ideal symmetry is achieved in accordance with this first aspect of the present disclosure with respect to the forces acting on the rotor and with respect to the temperatures acting on the rotor. Both the running properties and the long-term strength of the rotary vane expander are hereby increased.

In accordance with a particular embodiment of the first aspect of the present disclosure, the inner contour 10 of the housing is designed as asymmetric over the stroke region in this respect. In this respect, in particular the rotary region corresponding to the expansion phase is much larger than the rotary region in which the volume of the vane cells reduces again in order again to adopt a minimal volume at the start of the next stroke region. The expansion region 14, that is the region in which the spacing of the inner contour 10 from the axis of rotation of the rotor 11 increases, in this respect amounts to 75% of the total rotary range associated with this stroke in the embodiment, while the region 15 set to reduce the cell volume amounts only to 25%.

An improved efficiency of the rotary vane expander can be achieved by the asymmetric inner contour of the housing provided in accordance with the particular embodiment of the first aspect since a correspondingly extended expansion phase results.

In accordance with the now following second and third aspects of the present disclosure, the seal tightness of the rotary vane expander can now furthermore be improved. Leak losses which may be caused by the unfavorable changing gas conditions in the outlet region on the extension of the isentropic expansion in accordance with the first aspect of the present disclosure can hereby be reduced.

In this respect, an embodiment of the second aspect of the present disclosure is now shown in FIGS. 4 and 5. In accordance with this aspect, a compulsory guide ring 17 is used which forces the vanes 12 of the rotary vane expander into contact with the inner contour 10 of the housing 16. The compulsory guide ring 17 is in this respect rigidly connected to the housing 16. For example, the compulsory guide rings 17 can in this respect be arranged on both end faces of the rotor so that the inner edges of the vanes 12 are supported on the outer contour 18 of the compulsory guide ring.

The inner regions of the vane cells disposed opposite the outer edges now run on the outer contour 18 of the compulsory guide ring 17 which hereby controls the displacement of the vanes 12 in the radial direction. The outer contour 18 of the compulsory guide ring is designed in this case so that the vanes 12 are in contact with the inner contour 10 of the housing 16 in every rotary position of the rotor 11.

The contact region 19 of a vane 12 with the inner contour 10 of the housing is shown in a detailed view in FIG. 5. Since the contact region 19 has a radius of curvature r>0, the contact line 20 lies displaced by a specific interval from the radial direction or from a line 21 lying in the radial direction in all the angular positions of the rotor in which the inner contour 10 does not extend tangentially to the axis of rotation of the rotor. This displacement of the contact line 20 also results in the radial direction in a specific vertical offset h between the sectional line 21 between the center line of the vane extending in the radial direction and the inner contour 10 and the displaced contact line 20

In accordance with the present disclosure, this displacement of the contact line 20 and the vertical offset h caused hereby is taken into account in the design of the outer contour of the compulsory guide ring, just like a corresponding offset of a contact line of the vane on this outer contour. It can hereby be ensured that the vanes always contact the outer contour 10 of the housing without a gap despite the displaced contact lines. Gap widths of less than 10 μm can be realized over the total range of the angle of rotation by taking into account the displacement of the contact line.

Only two embodiments of a third aspect of the present disclosure are shown in FIGS. 6 and 7 by which a better sealing of the axial gap between the rotor 11 and the covers 24 of the housing is made possible. For this purpose, sealing disks 23 are used which are arranged between the rotor 12 and the covers 24. The sealing disks are in this respect divided into segments 23 which are respectively arranged between the vanes 12 of the rotary vane expander and which together form a seal ring.

In this respect, the end faces 22 of the rotor each have ring grooves 28 into which the sealing segments 23 are inserted. In this respect, in FIG. 7, the gaps 13 in the rotor 12 extending in the radial direction can also be seen, in which gaps the vanes are supported. The vanes in this respect have the same width as the rotor and their end edges thus respectively abut the inner sides of the covers 24. The further sealing of the individual vane cells in the axial direction is now made possible by the segments of the sealing disks.

The segments are in this respect pressed toward the inner surfaces of the covers 24 in a particular embodiment of the third aspect. In the embodiment shown in FIG. 6, this takes place with pressurization. For this purpose, a pressure passage 25 is drawn from the vane cell 26 to the rear of the segment 23. The segment is pressed through this toward the cover 24 by the pressure from the vane cell. Corresponding pressure passages are in this respect provided for all segments on both sides of the rotor.

In the embodiment shown in FIG. 7, the pressing takes place, in contrast, via a spring 27 which is arranged behind the segment 23. In this respect, for example, a corrugated spring or a compression spring can be used.

The sealing disk or the segments can be manufactured from a PTFE material or a ceramic material to minimize the friction losses. The segments of the disk are produced exactly in this respect to take account of the expansion of the material at higher temperatures.

A fourth aspect of the present disclosure will now be explained with reference to FIG. 8. An embodiment of a modular design of the rotary vane expander is shown there which realizes a variability of the stroke volume. In this respect, the shaft power can be set by the setting of the expander size.

The rotor is in this respect made up in accordance with the present disclosure from a plurality of rotor sections 11 and 11′ which are seated next to one another on a common shaft 30. The rotor sections 11 and 11′ are in this respect separated by a pressure plate 29 at which the axle 30 is supported. In this respect, identical rotor sections 11 and 11′ can be used. The stroke volume is in this respect divided by the pressure plates into mutually separate individual volumes.

Furthermore, the peripheral region of the housing is also made up of housing sections 16 and 16′ which can in particular have the same inner contour. They are likewise connected to the interposed pressure plate 29. Covers 24 can again be inserted at the two ends. The end-face sealing of the rotor sections with the covers and the pressure plates can in this respect in particular take place in accordance with the third aspect of the present disclosure.

The pressure plates 29 are in this respect advantageously likewise manufactured from ceramic materials or from materials coated with PTFE. Friction losses between the pressure plates and the rotors can hereby be minimized.

Depending on the desired stroke volume, the expander can now be set up from a corresponding number of rotor sections and housing sections. Expanders having different stroke volumes can hereby be manufactured without any greater conversion construction. The stroke volume is in this respect substantially determined by the number of rotors, with a corresponding extension of the shaft 30 being accompanied by the enlargement of the stroke volume.

In accordance with the fifth aspect of the present disclosure, provision is furthermore made that the support of the rotor shaft takes place by the use of ceramic ball bearings. In this respect, the balls of the ball bearing are made of ceramic material, while the guide rings of the bearing comprise steel.

It is possible hereby and optionally by the use of PTFE materials and/or ceramic materials in accordance with the present disclosure to operate the rotary vane expander in accordance with the present disclosure without lubrication.

In accordance with the present disclosure, two or more of the above-described aspects of the present disclosure can in this respect naturally be combined with one another. 

1. A rotary vane expander for generating mechanical energy from the expansion of a gaseous medium, comprising: a housing, an inlet and an outlet for the gaseous medium and having a rotor arranged in the housing; wherein an inner contour of the housing has two or more stroke regions which are in communication with the inlet for the gaseous medium such that the gaseous medium expands simultaneously in the two or more stroke regions during the operation of the energy recovery system.
 2. A rotary vane expander in accordance with claim 1, wherein the inner contour and/or control slits of the housing are made identical for all stroke regions.
 3. A rotary vane expander in accordance with claim 1, wherein the inner contour of the housing is made asymmetric with respect to a rotary region associated with a respective stroke, whereby the rotary region associated with the expansion phase makes up more than 50% of the total rotary region of the rotor associated with the respective stroke.
 4. A rotary vane expander for generating mechanical energy from the expansion of a gaseous medium, comprising: a housing, an inlet and an outlet for the gaseous medium and having a rotor arranged in the housing; wherein the vanes are guided by a compulsory guide ring on their side remote from the housing.
 5. A rotary vane expander in accordance with claim 4, wherein contact regions of the vanes with an inner contour of the housing have a radius of curvature greater than zero so that a contact line of the vanes with the inner contour is displaced with the rotary movement of the rotor on the radius of curvature of the contact regions, with the compulsory guide ring having a contour which takes this displacement into account.
 6. A rotary vane expander for generating mechanical energy from the expansion of a gaseous medium, comprising: a housing, an inlet and an outlet for the gaseous medium and having a rotor arranged in the housing; wherein sealing segments of a seal ring are arranged at end faces of the rotor between vanes for lateral sealing with the housing.
 7. A rotary vane expander in accordance with claim 6, wherein pressure elements are provided which press the sealing segments toward the housing.
 8. A rotary vane expander for generating mechanical energy from the expansion of a gaseous medium, comprising: a housing, an inlet and an outlet for the gaseous medium and having a rotor arranged in the housing; wherein the rotor comprises two or more rotor sections which are seated next to one another on a common axis and are each mutually separated by a pressure plate and/or the housing comprises two or more housing sections which are arranged next to one another in an axial direction of the rotor and surround the rotor.
 9. A rotary vane expander in accordance with claim 8, wherein the rotor sections and/or the housing sections are made identical and/or have the same outer contour or inner contour.
 10. A rotary vane expander in accordance with claim 9, comprising at least three rotor sections, with the housing having control slits in the peripheral region for controlling at least one of the inwardly disposed rotor sections.
 11. A rotary vane expander for generating mechanical energy from the expansion of a gaseous medium, comprising: a housing, an inlet and an outlet for the gaseous medium and having a rotor arranged in the housing; wherein the rotor of the rotary vane expander is supported via ball bearings having ceramic balls.
 12. A method of operating an energy recovery system including a rotary vane expander for generating mechanical energy from the expansion of a gaseous medium, comprising: a housing; an inlet; and an outlet for the gaseous medium and having a rotor arranged in the housing, wherein a gaseous medium flows into the rotary vane expander and expands there while outputting mechanical energy, and wherein an inner contour of the housing has two or more stroke regions which are in communication with the inlet for the gaseous medium such that the gaseous medium expands simultaneously in the two or more stroke regions during the operation of the energy recovery system.
 13. A method of manufacturing a rotary vane expander comprising a rotary vane expander for generating mechanical energy from the expansion of a gaseous medium having a housing, an inlet and an outlet for the gaseous medium and having a rotor arranged in the housing, wherein the rotor is built up of one, two or more rotor sections depending on a desired stroke volume, which, when two or more rotor sections are used, are set next to one another on a common axis and are each separated from one another by a pressure plate, and/or wherein the housing comprises one or more housing sections which, when two or more housing sections are used, are arranged next to one another in the axial direction of the rotor and surround the rotor. 